This research is designed to obtain detailed information about the molecular structure of pituitary growth hormone, prolactin, and related proteins of the pituitary and placenta, and to determine relationships between structure and biological activity. With completion of the sequence analysis of bovine growth hormone, studies are now directed toward the structural study of bovine growth hormone, studies are now directed toward the structural study of bovine prolactin and subprimate growth hormones and placental lactogens. Data on the primary structures will be used to examine homologies and evolutionary relationships with growth hormones and prolactins of other species and to search for potential homologies with other hormonal proteins. In collaborative studies, the biological activity of fragments of growth hormone and prolactin produced with cyanogen bromide and other specific cleavage reagents will continue to be evaluated in an attempt to define the area or areas of these molecules which are responsible for binding to target cells or constitute active sites or centers. Use will be made of growth hormone and prolactin covalently linked to Sepharose and other insoluble supports as a tool for exploring the interaction of these proteins with small molecules and macromolecular components of cell membranes and also to isolate specific antibodies for immunochemical studies. Studies will also be carried out to investigate the effects of growth hormone and prolactin and placental lactogens on enzymatic activities and macromolecular synthesis during development of the central nervous system.